The evaporative emission (EVAP) system is used to store fuel vapors as to reduce the amount of unburned fuel from escaping into the atmosphere. The EVAP purge solenoid is used to control the flow of fuel vapors from the EVAP canister to the intake manifold. The EVAP purge solenoid is commanded ON (pulse width modulation - PWM) whenever the EVAP system is in purge mode. Fuel vapors can be purged at anytime the powertrain control module (PCM) is in Closed Loop and the vehicle is not in a decel. The PCM controls the EVAP purge solenoid by controlling an internal driver that pulls the solenoid circuit to ground. The EVAP purge solenoid circuit is monitored for low and high voltage faults. DTC P0444 sets when the EVAP purge solenoid is commanded OFF and the feedback voltage at the PCM is low.
DTC Parameters
DTC P0444 will set if EVAP purge solenoid feedback voltage is less than 1.25 volts with EVAP purge solenoid commanded OFF when:
| • | The condition exists for longer than 0.5 seconds. |
| • | The ignition is ON. |
DTC P0444 diagnostic runs continuously with ignition ON and EVAP purge solenoid commanded OFF.
DTC P0444 is a type D DTC.
Diagnostic Aids
To locate an intermittent problem, use a scan tool to monitor EVAP PURGE - LOW VOLT or EVAP PURGE - OPEN test with ignition ON, engine OFF. When a fault, open or short to ground exists, the scan tool will display TEST FAIL for both tests.
The tests will fail only when the device is being commanded OFF and the voltage at the PCM is low. The tests update every 100 ms whenever the ignition is turned ON and the device is being commanded OFF via the scan tool or PCM.
The EVAP purge solenoid resistance is 19-31 ohms.
